1. Field of the Invention
This invention relates to semiconductor power diodes and a temperature gradient zone melting process for making the same.
2. Description of the Prior Art
Heretofore, commercial semiconductor diodes have been made by diffusion, alloying or epitaxial growth techniques. All such processes involve procedures wherein the optimum physical characteristics of the diodes are never achieved. Procedures are such that the introduction of contaminants inherent with the process techniques practiced degrade the physical characteristics of the diodes manufactured.
W. G. Pfann in his U.S. Pat. No. 2,813,048, teaches thermal gradient zone melting techniques for making various semiconductor devices. However, Pfann's devices had too many deficiencies to enable the process to be employed commercially.
An object of this invention is to provide a new and improved semiconductor power diode, the structure of which overcomes the deficiencies of the prior art.
Another object of this invention is to provide a new and improved semiconductor power diode which has maximum theoretical breakdown voltage as determined by the materials embodied therein.
Another object of this invention is to provide a new and improved semiconductor power diode which has a sharper P-N junction profile than any P-N junctions in prior art devices.
A further object of this invention is to provide a new and improved semiconductor power diode which has a faster recovery time and better switching characteristics than the prior art power diode devices.
A still further object of this invention is to provide a temperature gradient zone melting process to made a new and improved semiconductor power diode which is substantially free of defects such, for example, as metallic inclusions.
Other objects of this invention will, in part, be obvious and will, in part, appear hereinafter.